This invention relates to an intra-aortic balloon pump apparatus and, more particularly, to an intra-aortic balloon pump apparatus that makes it convenient to introduce a pressure transducer into the aorta.
An intra-aortic balloon pump apparatus basically comprises a catheter through which a fluid such as helium gas is passed, and a balloon attached to the distal end of the catheter which is cyclically inflated by feeding helium gas into the balloon from an external source via the catheter. The apparatus is inserted into the patient, usually through the femoral artery, either percutaneously or through an incision, and advanced until it lies within the thoracic aorta. There it is made to inflate and deflate synchronous with the heart so as to reduce the load on the left ventricle and increase the amount of coronary blood flow.
An example of an intra-aortic balloon pump apparatus capable of being inserted into a living body by percutaneous introduction (Seldinger technique) is disclosed in the specification of U.S. Pat. No. 4,362,150.
During use of an intra-aortic balloon pump apparatus, an electro-cardiogram and an arterial pressure signal are utilized to determine the time of inflation and deflation of the balloon. An example of such an apparatus is disclosed in the specification of U.S. Pat. No. 3,585,983. Here a pressure transducer is disposed at the distal end of the balloon and a signal produced by the pressure transducer is led out from the patient's body through the catheter. This conventional arrangement has the limitation that the balloon apparatus cannot be introduced into the patient percutaneously and, hence, the apparatus is limited to inhospital use.
A different arrangement is set forth in the specification of U.S. Pat. No. 4,077,394. Here a small tube leads from the tip of the balloon through the catheter, feeding aortic pressure to a sensor located externally to the patient. However, this apparatus possesses the same drawback mentioned above, namely the fact that percutaneous introduction is not feasible.
If the method of measuring aortic pressure described in U.S. Pat. No. 4,077,394 were to utilize the central tube mentioned in U.S. Pat. No. 4,362,150, then the apparatus could be applied in the same manner. However, the system still would be prone to considerable external noise and distortion of the pressure signal which would make computerized recognition of the pressure signal unreliable.